1. Field of the Invention:
The present invention relates to a wire-type window regulator or winder having a driver unit for rotating a drum to move a wire wound around the drum for lifting and lowering a panel of window glass coupled to the wire to open and close the window, and more particularly to an improved driver unit for use in such a wire-type window regulator.
2. Description of the Prior Art:
One conventional wire-type window regulator or winder is disclosed in Japanese Utility Model Publication No. 49-2336. The disclosed wire-type window regulator has a driver unit as shown in FIG. 1 of the accompanying drawings for moving a wire 10 to lift and lower a panel of window glass to open and close the window. The driver unit includes a shaft 8 rotatably supported on a base 6, a gear 7 and a drum 11 mounted on the shaft 8 in parallel spaced relation and rotatable with the shaft 8, and a motor 1 disposed on the base 6 for rotating the gear 7. As the motor 1 rotates, the gear 7 is rotated to cause the shaft 8 to rotate the drum 11 for thereby moving the wire 10 wound around the drum 11. In the known driver unit, however, the motor 1 and the gear 7 are directly coupled to each other. Therefore, when the motor 1 is forcibly stopped in response to arrival of the window glass at the fully closed or open position, the drum 11 is subjected to a shock due to the inertia of the rotating part of the motor 1. As a result, the wire 10 is unduly tensioned, and the requirement is that the wire 10 should be of a sufficient mechanical strength.
One solution to the above problem has been to use a damper as disclosed in Japanese Laid-Open Utility Model Publication No. 50-26516. As shown in FIG. 2 of the accompanying drawings, the driver unit disclosed in the above Publication No. 50-26516 has a shaft 8 rotatably supported on a base 6, a gear 7 and a follower 11a rotatably mounted on the shaft 8 in parallel spaced relation to each other, and a motor 1 for rotating the gear 7. The gear 7 has a recess 7a in which there is disposed a damper 12 having an attachment hole 12a in which a projection 11b of the follower 11a engages.
When the gear 7 is rotated by the motor 1, the follower 11a is rotated by the gear 7 through the intermediary of the damper 12 and the projection 11b to thereby lift or lower the window glass. When the window glass is stopped upon reaching its fully closed or open position, continued rotation of the gear 7 is dampened by the damper 12a as it is deformed, and such dampened rotation is transmitted to the follower 11a. Where the follower 11a comprises a drum 11 as shown in FIG. 3, any tensioning force acting on a wire wound on the drum 11 can be reduced.
With the driver unit shown in FIGS. 2 and 3, the shaft 8 is mounted on the base 6, and the gear 7 and the drum 11 are rotatably supported on the shaft 8. The gear 7 and the drum 11 are increased in thickness in the axial direction of the shaft 8 to provide sufficiently long bearing surfaces 7c, 11c supported by the shaft 8 for preventing the gear 7 and the drum 11 from wobbling in use. However, the thick gear 8 and drum 11 make the driver unit large in the axial direction of the shaft 8. The driver unit which is large in size is disadvantageous in that it reduces the size of a compartment having a window incorporating the window regulator.
Furthermore, there are a plurality of recesses 7a defined in the gear 7, add dampers 12 are disposed respectively in the recesses 7. The follower 11a is therefore rotated under a uniform force by the gear 7 through the dampers 12. After the driver unit is assembled, however, the dampers 12 are concealed from external view. Since there would be no wobbling produced between the gear 7 and the follower 11a if at least one damper 12 were disposed in one recess 7, it would be impossible to ascertain through visual inspection whether all dampers 12 are assembled in place. If not all dampers 12 were assembled, the dampening ability would be insufficient, failing to reduce the tensioning force which would be imposed on the wire.